1. Field of the Invention
This invention relates generally to the application of closures to containers and, more particularly, to apparatus for obtaining more precision in the initial application of a closure to the finish or neck of a container. It is particularly useful where conventional neck guides cannot be used with threaded closures.
2. Description of the Prior Art
Innovation in the bottling industry is very dependent on the ready availability of machinery for processing new types of containers and closures. For years, the crown was the dominant closure employed. A different type of closure was then developed, which comprised a cap shell of aluminum which was inserted over the threaded neck end of the container and then secured in place by rolling threads in situ into the walls of the cap shell. Such closures are commonly called roll-on caps.
The roll-on cap necessarily required a completely new applicating machine because not only was an axial force necessary to hold the closure in place on the bottle neck and effect a seal between the closure liner and the end of the bottle neck, but concurrently, a rotating movement had to be imparted to the thread forming rollers. There was no practical way that a conventional crown-type applicating machine could be modified to apply the new style roll-on closures and, as a result, the adoption of the new closure proceeded very slowly. It did proceed, however, and now machinery for applying roll-on closures is common.
In recent years, there have been significant developments in plastic technology, making the utilization of a threaded plastic closure completely feasible for use in the carbonated beverage field. For example, a threaded closure of the type shown in U.S. Pat. Nos. 3,987,921 and 4,016,996 has been shown to be commercially practicable, and an economically desirable change for the bottler to adopt if applicating machinery was available to assemble the plastic closure to the bottle neck.
Since the plastic closure required a concurrent application of an axial force to the top panel of the closure with a rotation of the closure relative to the bottle neck, it was desirable to utilize existing closure applicating machines for effecting the assembly of aluminum shells to bottle necks to apply the new style plastic closure, and thus minimize the new investment required by the bottler. This was accomplished by a number of modifications of capping heads which may be applied to existing roll-on closure applicating machines.
Some of the roll-on type applicating machines do not incorporate a sufficient rotational movement of the capping head as it approaches its lowermost position relating to the bottle to effect the complete threading of a closure onto the threaded bottle neck. Therefore, pre-tightening mechanisms were developed, which partially apply a threaded closure on the threaded neck of a bottle prior to a closure being engaged by the applicating head.
While the pre-tightening mechanisms have improved the operation of the capping process, the pressure to obtain ever higher line speeds has made the initial cap pick-up by the container finish or neck more critical to avoid operation problems. The neck or finish has previously been guided into cap pick-up position by a neck guide star wheel plate on the in-feed star wheel. This was satisfactory at lower speeds and when aluminum shells were placed on the necks to have threads rolled in place after initial cap application. However, threaded plastic closures can encounter cocking or cross threading problems which pre-tightening mechanisms may not correct at high speeds. Moreover, a neck guide plate may not be used in some bottling lines, e.g. when the cap applicating machine is being fed directly from a filling machine, and the filling bottle pedestal has a feeding machine height at the time of transfer to the in-feed star wheel of the cap applicating machine which will not permit acceptance of the bottle neck by the neck guide plate. Therefore, there is a need for an improved closure application system which includes a better apparatus for and a method of aligning the finish or neck of a bottle with a cap pick-up mechanism and pre-tightening apparatus.